From: "Måns Rullgård" <mans@mansr.com>
To: linux-kernel@vger.kernel.org
Subject: Re: [patch] perf: ARMv7 wrong "branches" generalized instruction
Date: Wed, 10 Aug 2011 20:16:17 +0100 [thread overview]
Message-ID: <yw1xmxfhoz5q.fsf@unicorn.mansr.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1108101452510.25186@cl320.eecs.utk.edu>
Vince Weaver <vweaver1@eecs.utk.edu> writes:
> On Wed, 10 Aug 2011, Will Deacon wrote:
>
>> > It turns out the branches event used (ARMV7_PERFCTR_PC_WRITE) only seems
>> > to count taken branches.
>>
>> It also counts exceptions and instructions that write to the PC.
>
> are those more common than not-taken branches?
Every function return and every PLT call would fall in this category.
> I'd think branch predictor statistics will be a bit off if only taken
> instructions are measured.
Clearly.
--
Måns Rullgård
mans@mansr.com
next prev parent reply other threads:[~2011-08-10 19:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-10 17:40 Vince Weaver
2011-08-10 18:33 ` Will Deacon
2011-08-10 19:01 ` Vince Weaver
2011-08-10 19:16 ` Måns Rullgård [this message]
2011-08-10 22:07 ` Will Deacon
2011-08-11 8:15 ` Ingo Molnar
2011-08-11 9:16 ` Will Deacon
2011-08-12 10:34 ` Ingo Molnar
2011-08-15 11:18 ` Will Deacon
2011-08-12 4:35 ` Vince Weaver
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